In general, HFC-134a is produced through the reaction of trichlene with HF. This process is effected not by a single step reaction but by a two step reaction each step having different reaction conditions. That is, trichlene is allowed to react with HF as a first step reaction, thereby forming 1,1,1-trifluoro-2-chloroethane (referred to as "CF.sub.3 --CH.sub.2 Cl" or "HCFC-133a" hereinafter), and then the thus formed HCFC-133a is allowed to react with HF as a second step reaction to obtain HFC-134a.
More particularly, a first step reaction represented by the following formula (1) is carried out, for example, under a pressure of 4 kg/cm.sup.2 G, at a temperature of 250.degree. C. and with an HF/trichlene mol ratio of 6/1. EQU CHCl.dbd.CCl.sub.2 +3 HF.fwdarw.CF.sub.3 --CH.sub.2 Cl+2 HCl (1)
Thereafter, a second step reaction represented by the following formula (2) is carried out, for example, under a pressure of 4 kg/cm.sup.2 G, at a temperature of 350.degree. C. and with an HF/HCFC-133a mol ratio of 4/1. EQU CF.sub.3 --CH.sub.2 Cl+HF.fwdarw.CF.sub.3 --CH.sub.2 F+HCl (2)
In consequence, the prior art HFC-134a production process comprises the steps of carrying out the first step reaction under the above conditions, purifying the product, re-adjusting conditions for the second step reaction, carrying out the second step reaction and then purifying and recovering the thus formed HFC-134a. Since distillation and separation steps are required for each of the reaction steps which are carried out under different reaction conditions, the prior art process has disadvantages in that it requires complex steps and is poor in energy efficiency.